Visible Light Transmission (VLT) describes the amount of visible light that passes through the lens of protective eyewear. It is expressed as a percentage.

Higher VLT values mean more light passes through the lens, resulting in brighter vision. Lower values produce darker lenses that reduce brightness.

When selecting laser safety glasses, both optical density and VLT must be considered. While strong filters may block hazardous laser wavelengths, they can also reduce visible light.

The goal is to achieve adequate protection while maintaining practical visibility for the task.

Manufacturers typically list VLT alongside wavelength and optical density specifications.

Understanding VLT helps users select eyewear suitable for their work environment.